Verified cavity graph
See every internal cavity, outside connection, bottleneck, drain, and vent.
Resin Safety Preflight
Hollow resin models without hiding a sealed failure inside.
Map every cavity, verify that drain and vent holes actually connect, protect fragile details, and recheck the model after every geometry change.
Last reviewed
Expected outcomeA hollowing plan designed for reliable drainage, washing, and curing.
Why hollow resin prints fail on the inside.
Hollowing saves resin and lowers the load on the part, but every enclosed cavity becomes a closed container. If liquid resin cannot leave it, the part can hold uncured resin that later leaks or splits the shell.
A hole in the outer surface proves little. It has to reach the cavity through a passage wide enough to drain and vent, and which end is high or low depends on the print orientation, not on how the model sits on screen. A model with several separate pockets needs an opening for each one.
Meshworthy builds a map of every cavity, traces its connection to the outside, and reports the narrowest point on each route. When a later edit changes the geometry, it discards the old result and checks again.
Checks included in this workflow.
Meshworthy shows the affected geometry, applies the selected constraints, and checks the exported result. Limitations remain visible when a result requires manual review.
Hole integrity
A visible hole only passes when it reaches the intended cavity in the exported result.
Keep Solid regions
Protect hair, fingers, cables, fire, and other details from unsafe global hollowing.
Dependent rechecks
Holes, scaling, splitting, and simplification automatically invalidate stale safety results.
From a solid model to a drainable one.
01Protect fragile detail
→Mark regions such as hair, fingers, and cables as Keep Solid, so hollowing leaves them alone.
02Inspect the inner surface
→Review the cavity structure and the local wall risks that hollowing creates.
03Place and trace openings
→Test drain and vent holes in your print orientation, and follow each route to its narrowest passage.
04Recheck after every edit
Scaling, splitting, plugging, simplifying, or moving a hole invalidates the earlier result and starts a fresh check.
What is free and what needs Pro.
Cavity and drain-path validation is free in the Mac app, so you can check a model that is already hollow before you print it. Creating the hollow, including Keep Solid regions, is part of the one-time Meshworthy Pro unlock, with no subscription.
What this does not do.
- Meshworthy validates geometry. It does not generate resin supports or replace the exposure, orientation, and layer review in your resin slicer.
- Hole size, resin handling, and washing depend on your printer and material. Treat the route check as evidence about geometry, not as a guarantee of drainage.
- There is no universal number of drain holes. The right count depends on the cavities, the orientation, and the narrowest passage.
How to hollow an STL without trapping resin.
Plan every cavity, bottleneck, drain path, vent path, protected detail, and final export in the actual print orientation.
More guides on this topic
About resin safety preflight.
How many drain holes do I need?+
There is no safe universal number. Meshworthy evaluates each cavity, orientation, bottleneck, and practical wash path.
Can part of a model stay solid?+
Yes. Keep Solid regions protect fragile details while larger volumes are hollowed.
Does Meshworthy generate supports?+
No. It validates geometry before slicing and hands the result to your preferred resin slicer.
Why does a visible hole still fail the check?+
A hole passes only when it reaches the intended cavity in the exported mesh. A hole that stops at a wall, or opens into a different pocket, leaves the target cavity sealed.
Does print orientation matter for drain holes?+
Yes. Drainage and venting depend on which regions are low and high in the orientation you print, so Meshworthy applies your print orientation when it checks each route.
What happens if I scale or split the model after hollowing?+
The earlier cavity result is invalidated and Meshworthy checks again, because scaling or splitting can change wall thickness and openings.
Know before you print.
On the Mac App Store. Diagnosis is free; Pro unlocks repair and preparation for $19.99, once — never a subscription. Model processing stays local.
Get Meshworthy for Mac ↗